Having trouble with decoding Ford part numbers - Ford Forum - Enthusiast Forums for Ford Owners

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Old 06-06-2010, 11:40 PM
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Default Having trouble with decoding Ford part numbers

I'm having trouble with decoding of Ford part numbers. By reading a FordForum post, plus info on other web sites, I've learned that the Ford part number consists of:
1st digit of prefix (letter)= Decade
2nd digit of prefix (number)= Year of decade
3rd digit of prefix (letter)= Car line
4th Digit of prefix (letter)= Engineering department
Basic part number
Suffix (letter) indicating the design revision

Using the example in a FordForum post (C5JZ-8600-N), the C5 would indicate 1965 and the N would indicate the fourteenth revision of the part.

My first question- does the C5 indicate the year that the part was first introduced, and not the model year of the vehicle the part is found in? In other words, if the same part was still being used in a 1971 model, would that part still be labeled C5 and not D1?

Many parts are used in multiple car lines. If a part was originally designed for the Falcon (car line D), and was subsequently used in the Mustang (car line Z), would that part in the Mustang have D, and not Z, as the third digit of the prefix?

When determining part/vehicle compatibility, must I match all digits of both the prefix and the basic part number, and then make sure the replacement part has a suffix with a letter equal to or higher than that of the part being replaced? Is there any digit in the prefix that can differ between compatible parts?

Also, I have a FOMOCO PCM labeled with part number 5L2A-12A650-JD; it reportedly was removed from a 2005 Explorer with the 4.0L V6. The first two digits of the prefix are number-letter, which does not comply with the format described above. Did Ford change the part number format with the start of the new century? Also, the suffix in my part number has two letters, not one. I'm guessing that one of them, perhaps the D, still indicates the design revision. Can anyone explain the meaning of the two letters?

Also, can anyone point me to a good database for determining vehicle compatibility?

Thanks in advance for any help you can provide!
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Old 05-31-2011, 03:53 PM
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Join Date: May 2011
Posts: 2

Hi there -

To answer your questions, starting at the first:
The prefix indicates the date when the part was last redesigned. So in your example, if a '71 was using the same radiator that was last redesigned in '65, the part number will be C5. If the part is redesigned in '72, it will then have a D2 part; if the application of the redesigned part is compatible with the '65-'71, the C5 part will be superceeded to the D2 part number and the C5 part will be discontinued.

The carline the part was originally designed for is what will be indicated in the bridge of the part number - so yes, a Falcon part (D) will remain a D if it is later used in a Mustang (assuming no redesign of the part occurs). If the part is redesigned, the year suffix will change to the year the part is redesigned, and the bridge will change to the current application (i.e. they discontinue the Falcon, but continue to use the part in the mustang in a redesign, at the redesign the part changes to Z).

The suffix only indicates revision in some instances, like an Alternator, Starter, etc. In other cases, the suffix refers to the specific usage of the part (like Fusion radiator grill is multiple pieces, AE5Z-8200-A, B, C, & D). Basic and prefix will determine a certain degree of compatibility, however many parts are superceeded, or will be superceeded to multiple parts, so there is still a lot of guesswork involved in trying to determine compatibility.

To answer your PCM question, starting at 1999, Ford changed the first 2 digits of the prefix; First digit X for 99, Y for 2000, 1 for 2001, etc. The second digit refers to the vendor producing the part if I'm not mistaken (like 3C4Z, 4C4Z are Blue Diamond parts). So in the case of your PCM, 5 indicates a 2005 part number. The suffix can have multiple letters, because it doesn't refer to revision, but rather application. (Like a 5L2A-12A650-DA is for a 4.0 V6, but say a 5.0 could be 5L2A-12A650-C - same year and basic but different applications). Also, the number on the part is the engineering number, not the replacing part number; you would be able to find the replacing number with the engineering number through a Ford Dealer.

The only good database in terms of part compatibility is a Ford Parts Catalog - Ford Catalog Advantage or similar that the dealers use. Fordparts.com is integrated to Ford Catalog Advantage, so it will give you the superceeded part numbers; however, the database only goes back 10 years on the site if I'm not mistaken.

Hope this helps.

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Old 06-29-2011, 08:13 AM
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Join Date: Jun 2011
Posts: 5

hey you get a detailed description for decoding here
Classic Mustang Part Number Decoding Guide
i suppose it will help you out
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